Model M stuck/repeating key?

[wumpyr]

Hello

I have a raven black ibm/maxiswitch M13 which works perfectly except for a single key - the Insert key.  It depresses fine, but if I use the xwindows tool xev to watch keyboard events, most normal Insert keypresses result in no registered key event, then after pushing the key several times it finally registers, however it continues to register as if I had held down the Insert key indefinitely  The only way to stop the key press loop is to press any other key.  what's up with that?

There doesn't appear to be any obvious problem with the key itself, it has the same tactile feel as every other key and the buckling spring appears to work fine.

I did try my other model m and it works fine, so it's only an issue with this keyboard.  Is this a membrane issue? a controller issue?

Not having insert is very annoying! this keyboard is directly connected to the ps/2 port on an ibm thinkpad port replicator.

any theories welcome.

thanks

[iMav]

I've seen this behavior on a Model M2 and it was definitely an issue with the membrane sheet contacts for that particular key.  

Not much you can do about it unless you want to engage Unicomp for a possible repair (which I'm not sure they can execute...depending on their parts availability).  Wouldn't hurt to give them a call or email though.

[wumpyr]

Hi iMav - thanks for the info, I may contact them.

btw, I've read this regarding repairing model M's.  Anybody else attempted it? success/failure?

thanks

[sandy55]

this regarding repairing model M's.  Anybody else attempted it? success/failure?

Well...I did twice. but I don't recommend that repairing for bad behavior of a single key.  I may try remapping tool and remove a spring from INS key or set an inserter beneath INS key.

[lowpoly]

Can't you just use the switch assembly from another (cheap) Model M?

And did you try to reseat the stem and clean the socket?

[sandy55]

lowpoly, adding a trackpoint assy would be a problem. I haven't yet examined how the assy is placed on the switching plate.  
lal and wellington may have a crue for it. they removed trackpoint assy from their Endurapro.

[lowpoly]

This is an M13, the trackpoint assy is put on top of the switch assy. I don't remember the specifics. bhtooefr had one, he might know if this will work.

[Mercen_505]

Major props to Sandy55 for posting that tutorial on replacing the plastic rivets on an M. Be *very* careful if you go that route.

I gave it a try earlier with my m13, but I ended up bending the backplate too much during reassembly, so several keys were sticking or double registering due to imbalanced pressure on the membranes. I also wound up with a weird situation in that one of the replacement springs I ordered from Clickykeyboard was actually defective: the spring was mounted on the hammer with the opposite orientation, so it wouldn't buckle properly! I didn't discover this until I had everything back and was reseating the keys... which meant that after all that hard work I still had a defective key!

I ended up buying another cheap M off Ebay and using the guts of that in my M13. It was an easy conversion, but I lost the trackpoint nub in the process. This is good, however, as I never liked it. I know I've desecrated a hideously rare keyboard, but I now have an excellent piece to code with at home and I don't ever intend to sell it

Also good timing as I just gave my dad my cherished '86 1390131 silver label M for Christmas and I was hoping to have the M13 ready for action before then. Turns out I got it working last night...heh. I'm gonna miss that keyboard... I'm not exaggerating when I say I've written well over a million lines of code on that board.


Edit:

Also, if you go that route you will have to convert the M13's 6 pin cable connector to a 4 pin one to get it working with the different board (you don't want a black keyboard with a grey cable, right?!). Let me know if you need the pinouts as I have them written down.

[bhtooefr]

I had one, but I believe the TrackPoint went through the board. :/

[lowpoly]

This is what I remembered:

The Model M13 has the TrackPoint mounted completely on top of the plastic plate that covers the top of the membrane, and then runs a cable between the keys around to the back of the board, where the keyboard/TrackPoint controller (it's all-in-one on the M13) resides.

(link to post)

[bhtooefr]

OK, I'll go with that, then, seeing as I had opened my M13 around the time I posted that.